Nonhyperbolic escape and changes in phase-space stability structures in laser-induced multiphoton dissociation of a diatomic molecule - art. no. 056211

The dependence of photodissociation of a diatomic molecule (vibrating accor ding to the Morse potential) on the frequency of the laser field that induc es it, is studied in the context of classical nonlinear dynamics. First., i t is observed that as the laser frequency increases towards the harmonic fr equency of the potential, a transition from stabilization due to Kolmogorov -Arnold-Moser tori to stabilization caused by the resonance stability islan d occurs. Then. considering the photodissociation as a nonhyperbolic half-s cattering process, we investigate the influence of these changes in the pha se space stability structures on dissociation dynamics via the examination of the fractal set of singularities appearing in the time-delay function of the initial state. It is found that the effective fractal dimension of thi s set (a finite-scale approximation of the exact dimension which is always equal to 1) and the percentage of its singularities provide a link between these changes and the dissociation rate.